Dental light using LEDs

ABSTRACT

A dental light comprises at least one light emitting diode light source configured to produce a light beam and at least one collimating lens system situated to receive the light beam. The collimating lens system is configured to collect and collimate the light beam. The collimating lens system can additionally modify the beam through controlled diffusion or shape the beam using an aperture.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/551,112, filed Aug. 26, 2019, now U.S. Pat. No. 11,092,310, which isa continuation of U.S. patent application Ser. No. 16/112,335, filedAug. 24, 2018, now U.S. Pat. No. 10,390,690, which is a continuation ofU.S. patent application Ser. No. 15/830,410, filed Dec. 4, 2017, nowU.S. Pat. No. 10,070,779, which is a continuation of U.S. patentapplication Ser. No. 15/290,705, filed Oct. 11, 2016, now U.S. Pat. No.9,833,133, which is a continuation of U.S. patent application Ser. No.13/281,379, filed Oct. 25, 2011, now U.S. Pat. No. 9,500,340, all ofwhich are incorporated herein by reference.

FIELD

This application relates to LED lights, and, in particular, an LED lightfor use in dentistry.

BACKGROUND

In the dental industry, dental lights, also known as dental operatinglights or dental operating luminaires, are used to illuminate apatient's mouth (oral cavity) while dental procedures are performed. Forexample, dental lights assist in the examination and diagnosis ofpatients, tooth reduction and preparation, color-shade matching, andrestoration.

Current dental lights use predominantly incandescent or quartz-halogenbulbs as the light source. These sources are also commonly used withreflectors, such as mirrors or other reflective surfaces. Light emittingdiode (LED) light sources have several advantages over these lightsources, including longer life, lower power consumption, and greatlyreduced radiant heat.

There are, however, several challenges to implementing LED light sourcesin dental lights. For example, quality of light is important in variousdental applications. The color rendering index (CRI) of an LED istypically lower than that of conventional light sources, making itdifficult for dentists to examine for soft tissue pathology and toperform color-shade matching with LED light.

Another design concern is that the dental light should create a lightpattern that reduces operator and patient discomfort. For example, it isdesirable to reduce operator eye fatigue, to reduce shadowing, and toreduce light incident on the patient's eyes. Thus, there are severalimportant considerations to take into account in the design of an LEDdental light.

SUMMARY

Described below are embodiments of a dental light having LED lightsource(s) that addresses some of the shortcomings of conventional dentallights.

According to one embodiment, a dental light comprises at least one lightemitting diode (LED) light source configured to produce a light beamalong a path, and at least one collimating lens system situated toreceive the light beam and configured to mix light within the light beamby controlled diffusion to increase color uniformity of the light beam.The at least one collimating lens system can comprise a diffuserconfigured to produce the controlled diffusion. The diffuser can be atransparent optical element having a microstructured surface. Thediffuser can be configured to impose a divergence on the received lightbeam of between about 0.5 and about 5 degrees, or of about 2 degrees.The at least one collimating lens system can comprise a first lens, asecond lens, and a diffuser positioned between the first and the secondlens. The first lens can be an aspheric collector lens and the secondlens can be a plano-convex collimator lens situated downstream of thefirst lens. The at least one collimating lens system can comprise anaperture and a diffuser, where the diffuser is configured to produce thecontrolled diffusion and is situated downstream from the aperture. TheLED light source can be a high brightness white LED.

According to another embodiment, a dental light comprises a plurality ofLED light sources configured to produce respective light beams alongrespective paths and a plurality of collimating lens systems eachsituated to receive the light beams and configured to mix light withinthe light beams by controlled diffusion to produce respective diffusedlight beams. The plurality of collimating lens systems can be spacedapart from each other and situated so as to direct the respectivediffused light beams towards a projection axis of the dental light. Theplurality of collimating lens systems can be arranged approximatelyequidistant from a central point so as to define a polygon-shaped array,or to define a substantially circular array. The central point can bealong the projection axis of the dental light. The plurality ofcollimating lens systems can be situated relative to each other suchthat the diffused light beams substantially overlap at a predeterminedillumination plane of the dental light. The diffused light beams canproduce respective beam patterns at the illumination plane, and thedental light can include at least one shaping lens configured to receivethe diffused light beams and to spread the respective beam patterns inthe illumination plane. The plurality of collimating lens systems can besituated relative to each other so as to reduce hard shadows of thediffused light beams at the illumination plane. The plurality ofcollimating lens systems can be situated relative to each other so as toreduce change in beam pattern size as distance from the illuminationplane varies. The illumination plane can be substantially perpendicularto the projection axis of the dental light. The illumination plane canbe located between about 550 and 850 millimeters, or between about 700and 750 millimeters, from the LED light sources along the projectionaxis.

In another embodiment, a dental light comprises at least one normal-modeilluminator and at least one cure-safe illuminator. The at least onenormal-mode illuminator can be formed from at least one LED light sourceand at least one collimating lens system. The at least one cure-safeilluminator can be formed from at least one LED light source and atleast one collimating lens system configured to produce a cure-safebeam. The at least one cure-safe illuminator can comprise a band passfilter configured to produce the cure-safe beam. Collimating lenssystems can be configured to mix light within the light beams producedby the LED light sources by controlled diffusion to increase coloruniformity of the light beams.

According to another embodiment, a dental light comprises at least onelight emitting diode (LED) light source mounted to a substrate and atleast one collimating lens system. The at least one LED light source isconfigured to produce a light beam along a normal axis that isperpendicular to the substrate at an approximate center of the at leastone LED light source. The light beam contains light having a pluralityof angles of propagation relative to the normal axis. The at least oneLED light source has a color rendering index (CRI). In oneimplementation, the at least one collimating lens system is situated toreceive the light beam and configured to limit the angles of propagationof light collected by the collimating lens system such that the lightemitted from the at least one collimating lens system has a CRI that isat least about 2 points greater than the CRI of the at least one LEDlight source. In another implementation, the at least one collimatinglens system is situated to receive the light beam and configured tolimit the angles of propagation of light collected by the collimatinglens system so as to produce a shift in CIE chromaticity coordinates ofthe LED light source towards a Planckian black body locus of at least0.002 units, or of at least 0.004 units. The shift can be such that CIEx and y chromaticity coordinates of the LED light source after beingshifted lie approximately on the Planckian black body locus. The atleast one collimating lens system can be configured to predominantlycollect light emitted from the LED light source having angles ofpropagation less than about 60 degrees. The at least one collimatinglens system can comprise an aperture configured to limit the angles ofpropagation of light collected by the collimating lens system.

According to another embodiment, a dental light comprises a plurality oflight emitting diode (LED) light sources spaced apart and mounted on asubstrate, each configured to produce respective light beams. The dentallight also comprises corresponding plurality of transmissive opticalsystems situated so as to receive the respective light beams andconfigured to collimate the light beams, thereby producing respectivecollimated light beams such that each collimated light beam produces abeam pattern at a predetermined illumination plane spaced from thesubstrate along an illumination axis of the respective transmissiveoptical system. The dental light also comprises a transparent shieldpositioned to receive the collimated light beams and configured torefract the collimated light beams along a refraction axis so as tospread the respective beam patterns along the refraction axis. Therefraction axis can be parallel to the shield. The shield can comprise aseries of lenses which extend along an inner surface of the shield in adirection perpendicular to the refraction axis, each of the lenseshaving a width along the refraction axis such that each collimated lightbeam is transmitted through more than one of the lenses. The shield cancomprise an array of cylindrical convex lenses perpendicular to therefraction axis to perform the refraction of the light beams. Thecylindrical convex lenses can be formed on an inner surface of theshield. The plurality of transmissive optical systems can be positionedsuch that the respective illumination axes form an angle of betweenabout 1 and about 10 degrees with a projection axis of the dental light.The illumination plane can be located at a distance of between about 550and about 800 mm from the substrate. The dental light can furthercomprise a rear housing and a front housing intermediate the shield andthe rear housing. The substrate can be mounted to an inside surface ofthe rear housing. The shield, the front housing and the rear housing canbe configured to be assembled together into an enclosed optical system.

According to another embodiment, the dental light comprises a housingformed of a thermally conductive material, a thermally conductiveprinted circuit board shaped to fit within the housing and positioned indirect thermal contact with the housing, and a plurality of lightemitting diode (LED) light sources coupled to the circuit board. Thedirect thermal contact between the printed circuit board and the housingfacilitates dissipation of heat generated by the LED light sources. Thethermally conductive printed circuit board can comprise a circuit layer,a dielectric layer comprising a dielectric material, and a thermallyconductive substrate layer comprising aluminum or copper. The dielectriclayer can have a thickness of about 0.003″ or less and the circuit layercan have a thickness of about 2 ounces/square feet or greater. Theplurality of LED light sources can be spatially separated on thethermally conductive printed circuit board by a distance of about 1.4″or greater.

According to another embodiment, a dental light comprises at least onelight emitting diode (LED) light source mounted to a substrate and atleast one collimating lens system comprising an aperture. The least oneLED light source is configured to produce a light beam along a normalaxis that is perpendicular to the substrate at an approximate center ofthe at least one LED light source. The light beam contains light havinga plurality of angles of propagation relative to the normal axis and theplurality of angles represents an angular distribution of the lightbeam. The aperture is situated to receive the light beam and configuredto shape the light beam such that the angular distribution is reducedalong a first axis perpendicular to the normal axis, thereby producing ashaped light beam. The reduced angular distribution along the first axiscorresponds with a reduction in patient eye glare at a predeterminedillumination plane. The aperture can have a substantially rectangularshape. The at least one collimating lens system can comprise collimatingoptics, and the aperture can be positioned between the LED light sourceand the collimating optics. The aperture can have a short axis thatcorresponds to the first axis.

In one example, the dental light further comprises at least one shapinglens situated downstream from the collimating optics, where the at leastone shaping lens being is configured to receive the shaped light beamand to spread the light beam in the illumination plane to further reducepatient eye glare. In another example, the collimating lens systemcomprises a diffuser configured to mix light within the light beam bycontrolled diffusion to increase color uniformity of the light beam. Thecollimating lens system can comprise a collector lens situated upstreamfrom the diffuser and downstream from the aperture. In another example,the at least one collimating lens system comprises a total internalreflection (TIR) collimator configured to mix light within the lightbeam to increase color uniformity of the light beam. The at least onecollimating lens system can comprise a first lens and a total internalreflection (TIR) collimator situated upstream of the first lens. Inanother example, the dental light further comprises a transparent shieldpositioned downstream from the collimating lens system and comprising anarray of cylindrical convex lenses.

According to another embodiment, the dental light comprises a pluralityof LED light sources spaced apart and mounted to the substrate and aplurality of collimating lens systems comprising respective apertures.Each LED light source is configured to produce respective light beamsalong respective normal axes, and each collimating lens system issituated to receive the light beams. The apertures are configured toproduce respective shaped light beams. The plurality of collimating lenssystems are situated so as to direct the respective shaped light beamstowards a projection axis of the dental light.

According to another embodiment, a dental light comprises at least onenormal-mode illuminator and at least one cure-safe illuminator. The atleast one normal-mode illuminator can be formed from at least one LEDlight source and at least one collimating lens system. The at least onecure-safe illuminator can be formed from at least one LED light sourceand at least one collimating lens system configured to produce acure-safe beam. Collimating lens systems can comprise aperturesconfigured to produce respective shaped light beams. The at least onenormal-mode illuminator is configured and situated to produce respectivenormal-mode beams directed towards a projection axis of the dentallight. The at least one cure-safe illuminator is configured to produce acure-safe beam directed towards the projection axis of the dental light.The at least one cure-safe illuminator can be configured tosubstantially reduce transmission of light by the cure-safe illuminatorhaving a wavelength below about 500 nanometers. The at least onecure-safe illuminator can comprise at least one collimating lens that isdyed so as to reduce transmission of light having a wavelength belowabout 500 nanometers through the at least one collimating lens.

According to another embodiment, a dental light comprises a plurality ofnormal-mode illuminators arranged approximately equidistant from acentral point to define a substantially circular array and at least fourcure-safe illuminators arranged equidistant from the central point andoutside of the substantially circular array. The central point can belocated along a projection axis of the dental light. Each normal-modeilluminator can be configured such that the respective normal-mode beamseach form an angle with the projection axis that is greater than zerobut less than 10 degrees, or that is between about 4 and about 5degrees. Each cure-safe illuminator can be configured such that therespective cure-safe beams each form an angle with the projection axisthat is greater than zero but less than 15 degrees, or that is betweenabout 6 and about 8 degrees.

According to another embodiment, a dental light comprises a rearhousing, a plurality of LED light sources arranged in a substantiallysymmetric array about a central point and coupled to the rear housing,and a pivot assembly attached to the rear housing at the central point.The central point corresponds substantially to the center of mass of thedental light. The pivot assembly can comprise a pivot arm capable ofrotational motion into a recess formed in the rear housing. The recesscan be situated between a first and a second of the plurality of LEDsources and formed such that the pivot arm fits into the recess at alower rotational limit. The pivot assembly can comprise an adjustabletension forked pivot bracket. The dental light can further comprise afront housing and a front shield secured to the front housing. The fronthousing is attached to the rear housing such that the plurality of LEDlight sources occupy an area between the front and the rear housing. Thefront housing can have a trough along at least a portion of itsperimeter. The dental light can further comprise a flexible gasketreceived in the trough, where the gasket serves to seal the connectionbetween the shield and the front housing.

In one example, the dental light comprises at least one handle securedto the front housing to facilitate positioning of the dental light. Theat least one handle has a rigid interior structure covered at leastpartially with a flexible tactile material. The flexible tactilematerial can have a Shore A durometer of less than about 95 and therigid interior structure can have a Shore A durometer of greater thanabout 95. The rigid interior structure of the handle can be formed byshaping a rigid thermoplastic substrate and the flexible tactilematerial can be a flexible thermoplastic that is molded over the rigidinterior structure. The flexible tactile material can have a Shore Adurometer of between about 70 and about 95 and the rigid interiorstructure can be an engineered resin.

According to another embodiment, a dental light comprises a housingunit, a circuit board shaped to fit within the housing unit and besecured to the housing unit, a plurality of light emitting diode (LED)light sources coupled to the circuit board, and an LED driver. Theplurality of the LED light sources comprises a first set of LED lightsources dedicated to normal mode operation and a second set of LED lightsources dedicated to cure-safe mode operation. The first and the secondsets are electrically independent. The LED driver is electricallycoupled to the first and the second set of LED light sources via thecircuit board and comprises a first and a second output. The LED driveris capable of supporting both the normal and cure-safe modes ofoperation by communicating with the first set via the first output andcommunicating with the second set via the second output. The LED drivercan comprise a buck-boost current regulator.

According to another embodiment, a dental light comprises a housingunit, a circuit board shaped to fit within the housing unit and securedto the housing unit, a plurality of light emitting diode (LED) lightsources coupled to the circuit board, a communications interface, and acable. The communications interface is configured to receive controlinformation from a user and to transmit data using a controller-areanetwork (CANbus) system. The cable is capable of transmitting the dataand of providing power to the LED light sources. The circuit board canbe coupled to at least one LED driver in communication with theplurality of LED light sources, and the CANbus system can be configuredto transmit messages to and to receive messages from the at least oneLED driver.

The foregoing and additional features and advantages will be morereadily apparent from the following detailed description, which proceedswith reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view showing a front side of an exemplary LEDdental light.

FIG. 2 is a perspective view of select component parts of the LED dentallight of FIG. 3 .

FIG. 3 is an exploded perspective view showing select component parts ofone specific implementation of the LED dental light of FIG. 1 .

FIG. 4A is an elevation view of an exemplary lens module and LED lightsource.

FIG. 4B is a cross-sectional view of a shaping lens and the lens moduleand LED light source of FIG. 4A.

FIG. 4C is an elevation view of an enlarged portion of the lens moduleand LED light source of FIG. 4A.

FIG. 4D is an enlarged view of the LED light source and aperture of FIG.4B.

FIG. 5A is an elevation view of an exemplary lens module and LED lightsource.

FIG. 5B is a cross-sectional view of a shaping lens and the lens moduleand LED light source of FIG. 5A.

FIG. 6 is a plot showing absorption spectra for photo-initiators andemission spectra for several dental lights.

FIG. 7A is a schematic of an optical system representing an exemplarynormal-mode illuminator.

FIG. 7B is a schematic of an optical system representing an exemplarycure-safe illuminator.

FIG. 8 is a cross-sectional view of an exemplary lens system forincreasing a color rendering index (CRI) of an LED light source.

FIG. 9 is a cross-sectional view of an exemplary lens system with anaperture.

FIG. 10 is a plot of chromaticity coordinates for exemplary LED dentallights described herein.

FIG. 11A is an elevation view of an exemplary shield to be used with anLED dental light.

FIG. 11B is a cross-sectional view taken along the line 11B-11B in FIG.11A.

FIG. 11C is a cross-sectional view taken along the line 11C-11C in FIG.11A.

FIG. 11D is an enlarged view of the region 11D in FIG. 11C.

FIG. 12 is an elevation view of another specific implementation of theLED dental light of FIG. 1 .

FIG. 13 is a cross-sectional view taken along the line 13-13 in FIG. 12.

FIG. 14 is an enlarged view of the region 14 in FIG. 13 .

FIG. 15 is a perspective view of a rear portion of an LED dental light.

FIG. 16 is an exploded perspective view of the component parts of anexemplary pivot assembly.

FIG. 17 is a side elevation view showing a range of rotational motion ofthe LED dental light.

FIG. 18 is a front elevation view showing a range of rotational motionof the LED dental light.

FIG. 19 is a schematic showing the illumination produced by an exemplaryLED dental light.

FIG. 20 is a schematic showing the illumination produced by the LEDdental light of FIG. 1 .

FIG. 21 is a schematic of an exemplary control circuit for an LED dentallight.

FIG. 22 is a schematic of an exemplary control system receiving userinput.

DETAILED DESCRIPTION

Referring to the drawings, and more specifically to FIG. 1 , anembodiment of an LED dental light 10 is illustrated. In FIG. 1 , the LEDdental light 10 comprises a housing 2 and several illuminators 6 a-6 l.The illuminators 6 a-6 l comprise LED light sources and various opticsfor modifying and shaping light emitted from the LED light sources. Forexample, each of the illuminators 6 a-6 l can comprise an LED lightsource and a collimating lens system, or other optics as describedherein. In the illustrated embodiment, the illuminators 6 a-6 l arearranged in a substantially symmetric pattern around a central point 7,and are symmetric with respect to a line M passing through the point 7.However, other arrangements of illuminators are possible. For example,illuminators can be arranged in other symmetric or asymmetric patterns.Also, although FIG. 1 illustrates a particular number of illuminators,more or fewer illuminators may be used depending on the desired luminousoutput of the LED dental light. In general, the light emitted by the LEDdental light should be sufficiently bright to allow dental diagnosis andtreatment.

The illuminators 6 a-6 l are positioned behind a shield 4 within thehousing 2. In the illustrated embodiment, the shield 4 comprises anarray of cylindrical lenses 3 and performs a shaping function on thelight emitted from the illuminators 6 a-6 l. As shown, each of theilluminators 6 a-6 l transmits light through more than one of thecylindrical lenses 3. The LED dental light 10 also has two handles 8secured to the housing 2 to facilitate positioning of the LED dentallight 10 by a dentist, dental assistant or other user. The housing 2 ofthe LED dental light 10 can be mounted to a flex arm or other structure(see, for example, FIGS. 17-18 ). In that manner, the light can bepositioned such that the illuminators 6 a-6 l illuminate a desired areaof a dental patient, typically an area within the oral cavity of thepatient.

Referring to FIG. 20 , the LED dental light 10 is shown illuminating anarea 110 contained within an illumination plane 114. For purposes ofillustration, only four illuminators 6 are shown. The illuminators 6 areshown producing light beams 106, 107, 108, 109 parallel to and alongrespective illumination axes 126, 127, 128, 129. The illuminators 6 canbe configured such that the light beams 106, 107, 108, 109 produce beampatterns at the illumination plane 114. The light beams 106, 107, 108,109 substantially overlap at the area 110, which can be referred to asan illumination area. In order that the light beams 106, 107, 108, 109substantially overlap at the area 110, the corresponding illuminationaxes 126, 127, 128, 129 are directed towards an axis 112.

The axis 112 intersects the illumination plane 114 within the area 110and can be referred to as a projection axis of the LED dental light 10.The projection axis of an LED dental light is generally defined by thedirection of the light it emits. Therefore, the projection axis can bedrawn between the LED dental light and the area illuminated by the LEDdental light. In some embodiments, the projection axis can be a centralaxis of the LED dental light. For example, the LED dental light 10 canhave a projection axis that passes through, or near to, the centralpoint 7.

In some embodiments, the illumination plane 114 corresponds to a focalplane of the light beams 106, 107, 108, 109. Generally, a focal planecan be the plane where light beams produced by a plurality ofilluminators substantially overlap to produce a composite pattern ofminimum size. Typically, the illumination plane 114 is located atbetween 550 and 850 millimeters from the LED dental light 10. In someexamples, the illumination plane can be located between about 700 mm and750 mm from the LED dental light, or approximately 700 mm from theshield 4 of the LED dental light 10. During use in a dental setting, theLED dental light 10 is desirably positioned such that the oral cavity ofthe patient is within the area 110.

In dental applications, it is typically desired that the illuminationplane be located at a predetermined distance based on standards withinthe industry. For example, ISO 9680:2007 is a standard for dentallights. This standard requires that the hard shadow generated by a diskhaving a diameter of 20 mm located at 50 mm from the illumination plane,positioned 700 mm from the dental light, be no greater than 12 mm in anydimension. Satisfaction of this standard can be demonstrated byreference to FIG. 19 . In the figure, a light source 115 having aprojection axis 112 is shown. For purposes of illustration, onlyapproximately half of the light source 115 is shown, the light source115 being divided along its projection axis 112. The radius of the lightsource 115 is shown as distance 113. The light source 115 produces alight beam 131 that is incident on a disk 129 located at a distance 119from an illumination plane 120, the disk having a radius 122. Light raysconfined entirely within the part of the light beam labeled 118 areblocked from reaching the illumination plane 120 by the disk 129, whilerays extending into the part of the light beam labeled 130 are notblocked by the disk 129 and reach the illumination plane. Applying theISO 9680:2007 standard, the radius 122 of the disk 129 is 10 mm, and thedistance 119 is 50 mm. A hard shadow is shown at the illumination plane120 having a radius 121, and the hard shadow is located at a distance117 from the light source, which is approximately 700 mm.

In order to satisfy the ISO 9680:2007 standard, the hard shadow radius121 must be no greater than 6 mm. LED dental lights described hereinsatisfy this standard. For example, in one implementation, the LEDdental light has a radius 113 of 62 mm, where the radius represents theouter edge of collimating lens systems used in the LED dental light.That is, the collimating lens systems are arranged along a circle with adiameter of 124 mm, such that the collimating lens systems are touchingbut within the circle. In such an implementation, the hard shadow isless than 12 mm in diameter. In other implementations, the LED dentallight has a radius 113 that is greater than 62 mm while stillmaintaining a hard shadow that is not greater than 12 mm in anydimension.

In general, as the radius 113 of the light source 115 is increased, thedental light may have increased position sensitivity. That is, the beampattern size can become more sensitive to changes in the distancebetween the light source and the illumination plane. For example, smallchanges in this distance can produce large variations in the beampattern size. It is generally desirable to reduce sensitivity becauseposition sensitivity makes the dental light difficult to position by theuser so as to provide a desired illumination of the patient. Thus, thesize of the LED dental light can be chosen to balance reduction in hardshadow size against increasing position sensitivity.

Another concern for dental light design is to provide users with theoption to alter the spectral power distribution of the dental light whenpreparing and/or applying light-curable dental materials. Thus, LEDdental lights described herein can, in some implementations, be operatedas dual-mode LED dental lights. That is, the LED dental light can beoperated in two modes: a normal mode and a mode compatible or safe foruse with light-curable dental materials, also described herein as a“cure-safe” mode. In the normal mode, the LED dental light emits whitecolored light for general use in a dental setting. In the cure-safemode, the LED dental light emits light that is substantially free ofwavelengths of light associated with the photo-initiated reaction oflight-curable dental materials and does not appreciably initiatepremature curing of the dental material. It is preferable for a dentistto operate in the cure-safe mode when light-curable dental materials arebeing used. For example, such materials are frequently used in dentalrestoration procedures as well as for sealants, varnishes, andorthodontia bracket bonding. This mode enables the operator toilluminate the oral cavity of a patient while utilizing a light-curabledental material in the illuminated area with reduced risk of prematurecuring of the material by the dental light.

More specifically, light-curable dental materials containphoto-initiators, which absorb certain wavelengths of light and start apolymerization of a resin monomer. A commonly used photo-initiator isCamphorquinone, which has a light absorption peak around 469 nm. Otherphoto-initiators typically have a similar or sometimes lower absorptionpeak (e.g., Phenylpropanedione and Lucirin TPO). In order for dentiststo use light-curable dental materials under the illumination of an LEDdental light and also avoid premature polymerization, the LED dentallight can be operated in the cure-safe mode. That is, the LED dentallight can be configured to reduce emission close to the polymerizationwavelength when a cure-safe beam is desired. For example, in someimplementations described herein, the LED dental light containsilluminators that are designed to function only in the cure-safe mode(cure-safe illuminators) and illuminators that are designed to functiononly in the normal mode (normal-mode illuminators). When the LED dentallight is placed in cure-safe mode, only the cure-safe illuminators areactivated. When the LED dental light is placed in normal mode, only thenormal-mode illuminators are activated.

In general, cure-safe illuminators are configured to reduce the emissionof light below the wavelength of 500 nm to reduce prematurepolymerization of the light-curable dental materials. However, a personof skill in the art would understand that this wavelength should beselected based on the particular material being used in the dentalprocedure. The emission of light from the cure-safe illuminators can bemodified through use of a band pass filter known in the art. Forexample, a filter can be incorporated into the optics within theilluminator. In some embodiments, the cure-safe illuminator includes acollimating lens system with a filter. For example, the collimating lenssystem can include one or more lenses that are tinted or dyed so as toreduce transmission of light having a wavelength of about 500 nm orless.

Referring to FIG. 6 , light absorption is plotted versus wavelength forthree different photo-initiators represented by lines E, F, G. As shown,all three photo-initiators demonstrate absorption peaks at wavelengthsof 500 nm or less. Line A represents an emission spectrum for an exampleLED dental light in accordance with this disclosure operating in normalmode. As shown, the LED dental light emits light at a range ofwavelengths, including below 500 nm. Thus, emission line A can bereferred to as white light emission. Line B represents the emissionspectrum for an exemplary LED dental light in accordance with thisdisclosure and operating in a cure-safe mode. As shown, this LED dentallight has significantly reduced emission of light below 500 nm. Line Crepresents the emission spectrum for a conventional tungsten-halogendental light, operated at its lowest intensity setting to minimize bluelight. As shown, this type of dental light exhibits a significant amountof blue light even when operating in this mode. Line D represents theemission spectrum for a multi-color LED source in a conventional dentallight where the blue LED source is turned off. As shown, this lightstill emits some light below 500 nm, and therefore may not be aseffective during dental applications using light-curable dentalmaterials as the LED dental light represented by line B. Comparing thedental light emission spectra of lines A, C and D to the photo-initiatorrepresented by line E, the lines A, C and D overlap line E significantlymore than line B. As a result, more premature polymerization will resultwith the lights represented by lines A, C and D than with the lightrepresented by line B.

Referring to FIG. 1 , the LED dental light 10 can be implemented as adual-mode light. For example, the illuminators 6 a, 6 b, 6 c, 6 d can becure-safe illuminators and arranged as shown in an approximately squarearray. That is, the four cure-safe illuminators can be positionedapproximately equidistant from the central point 7. Also, theilluminators 6 e, 6 f, 6 g, 6 h, 6 i, 6 j, 6 k, 6 l can be normal-modeilluminators and arranged as shown in an approximately circular array.In some embodiments, the illuminators 6 e, 6 f, 6 g, 6 h, 6 i, 6 j, 6 k,6 l are located along a circle with a diameter of between approximately100 and 150 mm. In one embodiment, a diameter of the illuminator isapproximately 32 mm and the centers of the LED light sources containedwithin the illuminators are located along a circle with a diameter ofapproximately 108 mm or greater. However, other arrangements ofcure-safe and normal-mode illuminators are possible. For example,illuminators, whether cure-safe or normal-mode, can be arranged alongany polygon shape or in other symmetric or asymmetric distributions. Ingeneral, the positions of the illuminators and the spacing between theilluminators can be selected to keep the size of the dental light smallwhile also reducing hard shadows (which can favor a larger distributionand tight spacing between illuminators) and position sensitivity.

In such a dual-mode implementation, the normal-mode illuminators and thecure-safe illuminators can include optics configured for theilluminator's desired function. For example, a schematic of an opticalsystem representing an exemplary normal-mode illuminator is shown inFIG. 7A. In the figure, an LED light source 383 is configured to producea light beam that is received by an aperture 384, which functions toshape the received light beam. Downstream from the aperture 384 is alens 387, which performs a collimating and collecting, or condensing,action on the received light beam. Downstream from the lens 387 is adiffuser 390, which functions to mix light within the received lightbeam to increase color uniformity of the beam. Downstream from thediffuser 390 is a lens 388, which performs a collimating, or condensing,action on the received beam. Downstream from the lens 388 is a shapinglens 389. As implemented in FIG. 1 , the shaping lens 389 function isperformed by the shield 4. However, the shaping lens can be a separateoptical element or set of optical elements.

In addition, a schematic of an optical system representing an exemplarycure-safe illuminator is shown in FIG. 7B. In the figure, an LED lightsource 483 is configured to produce a light beam that is received by alens 487, which performs a collimating, or condensing, action on thereceived light beam. Downstream from the lens 487 is a lens 488, whichalso performs a collimating, or condensing, action on the received lightbeam. As an exemplary cure-safe illuminator, the optical system of FIG.7B includes a mechanism for producing a cure-safe light beam, asdescribed above. For example, the lens 488 and/or 487 can be tinted ordyed so as to substantially reduce transmission of light having awavelength below about 500 nm. Alternatively, an additional opticalelement, such as a color tinted or dyed color filter, can be added tothe illustrated optical system to filter transmitted light. Downstreamfrom the lens 488 is a shaping lens 489. As implemented in FIG. 1 , theshaping lens 489 function is performed by the shield 4. However, theshaping lens can be a separate optical element or set of opticalelements.

As will become more apparent from the description below, normal-modeilluminators and cure-safe illuminators can include optical systemsdifferent from those shown in FIGS. 7A and 7B. Further, the optics shownin FIGS. 7A and 7B, along with their functions and alternatives, will bedescribed in more detail below.

FIG. 3 is an exploded view showing a specific implementation of the LEDdental light of FIG. 1 . FIG. 3 illustrates component parts of the LEDdental light 70. The component parts are expanded along a central axis9, which in some implementations can also be a projection axis of theLED dental light 70. A rear housing 50 forms of rear portion of the LEDdental light 70. The rear housing 50 can be made from various materialsknown in the art, such as various metals and plastics. The rear housing50 can include a recess 51 and a central area 52. In someimplementations, a pivot assembly (not shown, but see below at FIGS.15-16 ) is attached to the rear housing at the central area 52. Thepivot assembly can include a pivot arm that can rotate to fit within therecess 51. The central area 52 can be located at an approximate centerof mass of the LED dental light 70.

A substrate 30 can be mounted to the rear housing 50. The LED lightsources (not shown) are mounted to the substrate 30. The substrate 30can also include or be connected to various electronics for controllingthe LED light sources. The substrate 30 can be any printed circuit boardknown in the art, or other material used as a substrate for LED lightsources. Because LED light sources generate heat when activated, in someimplementations, the substrate 30 and the rear housing 50 can beconfigured so as to facilitate heat removal from the dental light 70.For example, the rear housing 50 can be a cast metal housing, and thesubstrate 30 can be a thermally conductive printed circuit board, suchas a printed circuit board with an aluminum, copper, or other thermallyconductive substrate, a dielectric layer and a circuit layer. Thesubstrate 30 can be mounted directly to the rear housing 50 so as toprovide direct thermal contact between the substrate 30 and the rearhousing 50. In some examples, the substrate 30 can be mounted to therear housing 50 with thermally conductive grease, compound, pads, orother material at the location of each LED light source on the substrate30 to further facilitate heat transfer. In some examples, the heatproduced by the LED light sources can be dissipated from the LED dentallight 70 without the need for active cooling or air vents in the dentallight. Avoiding air vents can enable the LED dental light 70 to be afully enclosed optical system and circuit board, if desired. Such afully enclosed system can reduce contamination and damage to the opticaland electrical components from dust, fluids, or cleaning chemicals.

Further explaining FIG. 3 , lens modules 40 are coupled to the substrate30. Generally, one lens module 40 can be coupled to the substrate 30 foreach LED light source mounted to the substrate 30. Each lens module 40can be positioned to receive the light beams produced by respective LEDlight sources. Each lens module 40 comprises optics described herein tomodify and shape the received light beam. For example, the lens modules40 can include optics to collect, collimate, and/or condense the lightbeams emitted from the LED light sources. However, other optics can alsobe used in the lens modules 40.

The lens modules 40 can be mounted to the substrate 30 using opticalbases 31, 32, 33, 34, which can be mounted to the substrate 30, e.g.,with screws or other fasteners. For example, the lens modules 40 cantwist and lock into the bases 31, 32, 33, 34. In general, the opticalbases 31, 32, 33, 34 function as an intermediary structure to facilitatecoupling of the lens modules 40 to the substrate 30. Thus, otherstructures can be used in place of the optical bases to perform thisfunction. Alternatively, the lens modules 40 can be mounted directly tothe substrate 30 without use of an optical base or other intermediarystructure.

An optional front housing 54 fits over the lens modules 40 and issecured to the rear housing 50. The front housing 54 is typically formedso that it does not obstruct light transmitted through the lens modules40. For example, the front housing 54 can be situated such that each ofthe lens modules 40 corresponds to a hole 55. The front housing 54 canalso act as a decorative mask for the optics used in the LED dentallight 70.

Handles 8 can be attached to the front housing 54, or alternatively tothe rear housing 50, by any suitable approach, such as by using screws56 or other fasteners, and can be removable. For example, the handles 8can be mounted by a quick release, non-tooled connection to allow thehandles to be disconnected and separately run through a dishwasher orsterilizer. In general, the handles 8 can be large, ergonomic grips witha rubberized grip surface which allows the user to move the LED dentallight 70 with ease and reduced hand strain. The handles 8 can have arigid interior structure covered at least partially with a flexibletactile material. The rigid interior structure can be formed by shapinga rigid thermoplastic substrate. The substrate can be a high strengthengineered resin, which can have a mineral fill, glass fill, or otherfill for increased rigidity. The flexible tactile material can be athermoplastic that is molded over the rigid interior structure. In someembodiments, the flexible tactile material has a Shore A durometer ofless than 95, and the rigid interior structure has a Shore A durometerof greater than 95. Further, in some examples, the flexible tactilematerial has a Shore A durometer of between about 70 and 90. The handles8 can be horn-shaped with curved ends 5 on the top to allow the use ofslip-on asepsis barriers (not shown). This shape, as well as therubberized surface, can help prevent the barriers from slipping offduring use.

Decorative features 60, 61, 62 are optionally mounted to the fronthousing 54, if present, or to the rear housing 50 if the optional fronthousing is not present. For example, the decorative features 60, 61, 62can be labels that when applied hide fasteners such as screws used tosecure together the component parts of the LED dental light 70. In thismanner, the fasteners are no longer visible from the exterior of the LEDdental light 70, and the fasteners no longer act as collection areas forcontaminants.

The front shield 4 is then secured to the front housing 54, if present,or to the rear housing 50 if the optional front housing is not present.For example, the front shield 4 may have an integrated snap feature thatallows the shield to snap on to the front housing 54. The shield 4 ismade of a transparent material, and can function as a dust shield. Theshield 4 can be flat with smooth edges that wrap over a portion of thefront housing 54. A flexible gasket 57 can be fitted in a trough 53around the perimeter of the front housing 54. Alternatively, the shield4 can include a trough or both the front housing 54 and the shield 4 caninclude the trough. In this manner, the shield 4 can be sealed againstthe front housing 54. Such a seal can make the LED dental light 70easier to clean by protecting the lens modules 40 and any electronicsconnected to the substrate 30 from damage caused by water or cleaningchemicals. Thus, the shield 4 can reduce the need to remove componentsof the LED dental light 70 in order to clean them. Alternatively, theshield can be flat and secured to the dental light by an adhesive bondor by a bezel wrapping over the front face of the shield with or withouta seal.

The front shield 4 is shown in FIG. 3 without an array of lenses 3 (seeFIG. 1 ), which perform a final shaping function on received lightbeam(s). If such shaping is desired, shaping lenses can be included asseparate elements from the shield 4. For example, shaping lenses can beincluded in the modules 40. However, in some embodiments, the shield 4can also serve a light shaping function. For example, an array ofshaping lenses can be mounted to the shield 4, or an array of lenses canbe integrated into an inner or outer surface of the shield 4.

FIG. 2 provides an enlarged view of individual lens modules mounted tobases 31, 32, 33, 34 of the LED dental light of FIG. 3 . In the figure,lens module 40 is shown to include a lens housing 41, which holds inplace various optics 42 such as, e.g., a collimating lens system and/orother optics as shown in FIGS. 4, 5 and 7-9 and described herein. Forclarity, the optics are not shown in FIG. 2 , and the region 42represents the space in which the optics are located. In the figure,lens modules 11, 21, 28 are mounted to the base 34. Further, lensmodules 12, 22, 23 are mounted to the base 31, lens modules 13, 24, 25are mounted to the base 32, and lens modules 40, 26, 27 are mounted tothe base 33. The bases 31, 32, 33, 34 are then mounted to the substrate30. LED light sources (not shown) are mounted to the substrate 30 suchthat each lens module corresponds to an LED light source.

FIGS. 4 and 5 provide additional views of exemplary lens modules andoptics contained therein. Specifically, FIG. 4A is an elevation view ofan exemplary lens module 80 and LED light source 83, with an aperture 84having a substantially rectangular shape. As shown, the lens module 80includes a lens housing 81 and optics 82 held in place by the housing81. For clarity, the optics 82 are not shown in FIG. 4A. FIG. 4B is across-sectional view of the lens module 80 and LED light source 83, andillustrates exemplary optics 82. The lens curvatures and spacing betweenoptical elements shown in FIG. 4B are schematic and not drawn for scale.For purposes of illustration, the lens housing 81 is not shown, and theaperture 84 is shown to be included in the optics 82. The aperture 84can be part of an optical base to which a lens module is mounted, or theaperture 84 can be part of the optics in a lens module and held in placeby the lens housing.

In FIG. 4B, the LED light source 83, mounted to the substrate 30, isconfigured to produce a light beam that is received by optics 82, whichinclude lenses 87 and 88, and then received by shaping lens 89. Theoptics 82 represent an exemplary collimating lens system. Thus, theoptics 82 can be referred to as a collimating lens system. However, acollimating lens system can include fewer or more optics than theoptical system 82. In general, a collimating lens system includes atleast one optical element, such as one or more lenses, configured toperform collimating action on a received light beam. A collimating lenssystem can also function to collect and/or condense light. A collimatinglens system can include other optics in addition to those capable ofperforming collimating, collection, or condensing action. Such otheroptics include lenses and other devices known in the art, or describedherein, for shaping, mixing, filtering, focusing or otherwise modifyinglight. The components of a collimating lens system are typicallytransmissive, i.e., the components transmit rather than reflect themajority of received light. The components of a collimating lens systemcan be selected so as to produce the desired beam pattern at theillumination plane of the LED dental light.

Referring to FIG. 4B, an axis 85 defines an optical axis of the optics82 and intersects the optics 82 at an approximate center. The axis 85can be referred to as an illumination axis when it is parallel to anddirected along the direction of propagation of light emitted from theoptics 82 or the lens module 80. In the illustrated implementation, theaxis 85 is shown to be displaced from an axis 91 by an angulardisplacement 86. The axis 91 corresponds to a normal axis of the LEDlight source 83. That is, the axis 91 is perpendicular to the substrate30 at an approximate center of the LED light source 83. Preferably, theillumination axis 85 intersects axis 91 at the approximate center of theLED light source 83.

In general, the angular displacement 86 can be selected to generate adesired illumination by the LED dental light at the illumination plane.For example, if the LED dental light includes more than one LED lightsource and collimating lens system, the angular displacement 86 for eachlens system can be selected such that the light beams transmittedthrough each lens system substantially overlap at the illumination planeof the LED dental light. For example, the angular displacement 86 foreach collimating lens system can be selected such that respectiveillumination axes are directed towards the propagation axis of thedental light. In some embodiments, the angular displacement 86 isapproximately zero. In other embodiments, the angular displacement 86 isgreater than zero but less than 15 degrees. In some embodiments, theangular displacement 86 is between 4 and 5 degrees, while in otherembodiments the angular displacement 86 is between 6 and 8 degrees. In aparticular embodiment, the angular displacement 86 is about 4.5 degrees,while in another particular embodiment the angular displacement 86 isabout 7 degrees. Each collimating lens system of an LED dental light canhave the same angular displacement or the lens systems can have avariety of different angular displacements.

Referring to the optics 82 in FIG. 4B, the light beam produced by theLED light source 83 is received first by the aperture 84. FIG. 4C is anenlarged view of a portion of the lens module 80 and LED light source83, and shows the aperture 84 having a short axis 93 and a long axis 92.FIG. 4D is an enlarged view of the LED light source 83 and the aperture84. The LED light source is desirably a white light source, and can beany LED light source known in the art. In some implementations, the LEDlight source is a high bright white LED with a domed aspheric lens. Whenhigh quality of light is desired (to be explained further below),exemplary LED light sources can include those which have qualifyingparameters such as Correlated Color Temperature (CCT) of about 5000Kelvin, single-chip construction, a Color Rendering Index (CRI) greaterthan 80, and International Commission on Illumination (CIE) chromaticitycoordinates close to the Planckian black body locus (as measured whenthe LED light source is incorporated into the LED dental light).Components that exhibit such parameters are available from, for example,Phillips, Everlight, Nichia, and others and can be selected fromNichia's NCSW119, NCSW219, NVSW119, and NVSW219 series of LEDs, as justsome examples. Of course, other equivalent LEDs could also be used.

The light produced by the LED light source 83 can be described as alight beam propagating along the normal axis 91 away from the substrate30. In general, an LED light source emits light in many differentdirections. Thus, the light beam produced by an LED light sourcecontains light having a plurality of angles of propagation measuredrelative to the normal axis 91. These angles of propagation can bereferred to as an angular distribution of the light beam. When the lightbeam emitted from the LED light source 83 is transmitted through theaperture 84, the angles of propagation of the light in the light beamare reduced based on the shape of the aperture. In FIG. 4D, the angulardistribution of the light is reduced along an axis 95, which isperpendicular to the normal axis 91. In this manner, the aperture 84functions to shape the light beam emitted from the LED light source 83.The axis 95 corresponds to the short axis 93 of the aperture 84.However, in the implementation shown in FIG. 4D, the axis 95 is notparallel to the short axis 93 of the aperture 84 because the angulardisplacement 86 of the optics 82 is non-zero. In some embodiments, theaxis 95 may be parallel to the short axis 93 of the aperture 84.

FIG. 9 further illustrates this shaping function of an aperture. FIG. 9is a cross-sectional view of an exemplary lens system with an aperture684. Lines 610, 611, 612, 613, 620 represent rays of light propagatingfrom the LED light source 683. The area between lines 611 and 613represents an angular distribution of the light beam emitted from theLED light source 683. The angles of propagation of the light in thelight beam can be measured from the normal 691, which is perpendicularto the LED light source 683 at an approximate center. As shown in thefigure, the aperture 684 accepts the light ray 620, which is received bythe lens system comprising lenses 687 and 688, while the light rays 610and 612 are rejected by the aperture 684 and are not received by thelens system. In this manner, the aperture 684 functions to reduce theangular distribution of the light emitted from the LED light source 683along an axis 695 that is perpendicular to the normal 691.

Referring back to FIGS. 4A-4D, the illustrated aperture has an obroundshape with straight sides and rounded ends. Although the aperture 84 issubstantially rectangular in shape, the aperture 84 can have a differentshape. For example, the aperture 84 can be more or less rectangular, ormore or less oval, in shape. The aperture 84 can be symmetric orasymmetric. Further, the edges of the aperture can be flat or angled.Compare, for example, aperture 84 of FIG. 4D to aperture 684 of FIG. 9 .Angled edges may be helpful for reducing reflection of light off theaperture, causing stray light outside of the desired illuminationpattern of the dental light. In general, the size, shape and position ofthe aperture 84 can be selected so as to reduce patient eye glare. Alight beam transmitted through a rectangular-shaped aperture can createan oval or rectangular-shaped beam pattern at the illumination plane.Because a patient's eyes are located fairly close to the oral cavity, itis desirable for dental lights to emit light that is shaped so as toreduce light directed toward the eyes and thereby reduce eye glare. Forexample, when the illuminated region corresponds to the patient's oralcavity, the ISO 9680:2007 standard requires that the illuminance at 60mm from a center of the illuminated region along the illumination plane(and towards the patient's eyes) be less than 1200 lux. The shape of theaperture 84 can be chosen so as to satisfy this standard such as byfurther reducing the light in the direction of the patient's eyes.Additionally, the position of aperture 84 relative to the optics 82 canbe selected so as to achieve a desired beam pattern shape at theillumination plane.

In general, the aperture 84 is an optional element that may or may notbe included in the lens module 80 or in optics 82. Thus, illuminatorsdescribed herein may or may not include such an aperture. Typically, theaperture 84 is included in a normal-mode illuminator. A cure-safeilluminator may not include an aperture 84 when the eye glare problemsdescribed above are not significant.

Referring to FIG. 4B, after the light is shaped by the aperture 84, itis received by lens 87. Lens 87 can be any aspherical collector lens orother collection element. For example, lens 87 can be a custom designedmolded acrylic, polycarbonate, glass or other suitably transparent lens.In general, lens 87 acts as a collection element to perform collimatingaction on a received light beam. Downstream from lens 87 is lens 88.Lens 88 can be any plano-convex collimator lens, Fresnel lens or othercollimating lens. For example, lens 88 can be a custom designed moldedacrylic, polycarbonate, glass or other suitably transparent lensproviding secondary collimation on a received light beam. Together, lens87 and lens 88 provide desired collection, collimation, and/orcondensing of the light emitted from the LED light source 83 andtransmitted through the aperture 84. In general, lens 87 and lens 88 canbe selected to produce a desired beam pattern at a desired distance fromthe LED light source 83. For some dental applications, it is desirableto have a substantially collimated beam directed towards the patient'soral cavity. In that case, lenses 87 and 88 can be selected so as toproduce a collimated beam at the illumination plane. A person skilled inthe art will understand that more or fewer lenses than lens 87 and lens88 can be selected to achieve this desired result.

Referring to FIG. 4B, an optional diffuser 90 is shown in between lens87 and lens 88. The diffuser 90 is configured to mix light within alight beam received from lens 87 in order to increase color uniformityof the light beam. For example, the mixing can be such that ahomogenized beam is produced at the illumination plane. That is, thecolor of the light is substantially uniformly throughout the light beamat the illumination plane. Typically, the light emitted by an LED lightsource has a non-uniform spatial and angular distribution of color. Forexample, the spectral power distribution (and hence color) of the lightbeam can vary across the angular distribution of the LED and laterallyacross the emitting surface of the LED chip. Such color non-uniformitycan result in a beam pattern at the illumination plane withobjectionable color non-uniformity, such as bands of color. A diffusercan be used to reduce this undesirable effect by mixing the spatiallydistributed colors into a more homogeneous light beam, such as byscattering light to a limited extent. However, if the diffusion isunlimited, or to a large degree, the beam pattern at the illuminationplane may become unacceptably large. Thus, the degree of diffusion canbe selected to balance the degree of mixing with the overall size of thebeam pattern. As used herein, this balancing is referred to ascontrolled diffusion. That is, controlled diffusion is diffusion that islimited or that produces an incremental increase in the divergence of alight beam. It can also be referred to as angularly limited diffusion,weak refraction or weak diffraction. In general, a diffuser can becharacterized by the divergence angle that it imposes on a receivedbeam. Preferably, a controlled diffuser induces a small divergence angleon a substantially collimated light beam. Typically, a controlleddiffuser is a diffuser that induces a divergence angle that is less than10 degrees.

Referring to FIG. 4B, the diffuser 90 can be any device capable ofproducing controlled diffusion, such as, but not limited to, a lightdiffusing film or sheet separate from or attached to lens 88, anengineered diffuser, a pillow lens, an array of diverging microlenses,or a transparent optical element having a microstructured surface. Forexample, optical elements having a microstructured surface are availablefrom commercial suppliers such as Luminit, RPC Photonics, and FusionOptix. Desirably, the diffuser 90 has a high transmission efficiency andis substantially achromatic. In a particular implementation, thediffuser 90 is a transparent optical element having a microstructuredsurface, where the surface comprises random, non-periodic threedimensional holographic relief structures. In another implementation,the diffuser 90 is a transparent optical element having a periodicmicrostructured surface.

As shown in FIG. 4B, the diffuser 90 can be attached to or integratedinto the lens 88. However, the diffuser 90 can be a separate elementbetween lens 87 and lens 88. The diffuser 90 can also be located beforelens 87, or at other locations within optics 82. In someimplementations, the diffuser imposes between about 0.5 and about 5degrees divergence on incident light. In other implementations, thediffuser imposes approximately a 2 degree divergence.

Typically, the diffuser 90 is included in a normal-mode illuminator. Acure-safe illuminator typically does not include a diffuser 90 when thecolor non-uniformity issues described above are not significant.

As an alternative to or in addition to the diffuser 90, otherlight-mixing devices can be used in the optics 82. Such light-mixingdevices include, but are not limited to, a light pipe, a total internalreflection (TIR) collimator, TIR optical fiber, microlens array, otherlenslet array, or combination thereof. Such light-mixing devices can beincorporated into the optics 82 and function to mix light within thelight beam received from lens 87 in order to increase color uniformityof the light beam. Depending on the type of light-mixing deviceselected, one or more of the lenses 87 and 88 may not be needed toproduce the desired illumination at the illumination plane. For example,if the light-mixing device is a TIR collimator, then the lens 87 may notbe needed. Alternatively, if the light-mixing device is a TIRcollimator, then neither lens 87 nor lens 88 may be needed.

Referring to FIG. 4B, light transmitted through the lens 88 is receivedby shaping lens 89. The shaping lens 89 provides a final shaping of thelight beam emitted from the LED light source 83. In general, the shapinglens 89 modifies the beam so that it has a desired shape at theillumination plane. For example, it is typically desirable that thelight at the illumination plane have an oval or rectangular shape inorder to reduce patient eye glare. The shaping lens 89 can be integratedinto or attached to the shield of the LED dental light. However, theshaping lens 89 can be a separate element from the optics 82 and fromthe shield. Although shown in FIG. 4B as a separate element from optics82, the shaping lens 89 can be a part of the optics 82 and situatedwithin the lens module 80. Further, the shaping lens functionality canbe integrated into other lenses in the optics 82, such as lens 88 or 87,making an additional shaping lens 89 unnecessary. In some embodiments,the shaping lens 89 is an array of cylindrical lenses.

FIG. 5A is an elevation view of another exemplary lens module and LEDlight source. As shown, a lens module 180 includes a lens housing 181and optics 182. For clarity, the optics 182 are not shown in FIG. 5A.FIG. 5B is a cross-sectional view of FIG. 5A, and illustrates exemplaryoptics 182. The lens curvatures and spacing between optical elementsshown in FIG. 5B are schematic and not drawn for scale. For purposes ofillustration, the lens housing 181 is not shown in FIG. 5B. An LED lightsource 183, mounted to the substrate 30, is configured to produce alight beam that is received by optics 182. The optics 182 represent anexemplary collimating lens system, and comprise a lens 187 and a lens188. Lenses 187 and 188 can be selected from lenses described herein, orothers known in the art. In general, lens 187 and lens 188 can beselected to produce a desired beam pattern at the illumination plane.Light emitted from optics 182 is then transmitted through a shaping lens189, which can be any shaping lens described herein.

Referring to FIG. 5B, an axis 185 defines an optical axis of the optics182 and intersects the optics 182 at an approximate center. The axis 185can be referred to as an illumination axis when it is parallel to anddirected along the direction of propagation of light emitted from theoptics 182 or the lens module 180. In the illustrated implementation,the axis 185 is shown to be displaced from an axis 191 by an angulardisplacement 186. The axis 191 is a normal axis that is perpendicular tothe substrate 30 at an approximate center of the LED light source 183.Preferably, the axis 185 intersects axis 191 at the approximate centerof the LED light source 183.

The optics 182 and the LED light source 183 can form an exemplarycure-safe illuminator. When used in this manner, the optics 182 can beselected so as to produce a cure-safe beam. As described above, a filtercan be incorporated into the cure-safe illuminator to produce thecure-safe beam. For example, lens 188 can be dyed or tinted such thattransmission of wavelengths of light below about 500 nm is substantiallyreduced. Alternatively, a film that is dyed or tinted could be attachedto lens 188. In another example, lens 187 can be so modified. However,tinting of lens 188 may be preferred over tinting of lens 187 when thelens 188 is of more uniform thickness than lens 187. Uniform lensthickness allows for more consistent attenuation of blue light whilereducing excessive attenuation of other wavelengths. In some examples,the filtering can be performed by an element separate from lenses 187and 188.

In an example embodiment of a dual-mode LED dental light, theilluminators 6 e-6 l shown in FIG. 1 can be normal-mode illuminators andthe illuminators 6 a-6 d can be cure-safe illuminators. Each of thenormal-mode illuminators 6 e-6 l can include an LED light source andoptics as illustrated in FIG. 4B. Furthermore, the angular displacement86 of the normal-mode illuminators can be between about 4 and 5 degreesso that the illuminators 6 e-6 l produce light beams that substantiallyoverlap at the illumination plane of the LED dental light 10. Each ofthe cure-safe illuminators 6 a-6 d can include an LED light source andoptics as illustrated in FIG. 5B. Furthermore, the angular displacement186 of the cure-safe illuminators can be between about 6 and 8 degreesso that the illuminators 6 a-6 d produce light beams that substantiallyoverlap at the illumination plane.

As stated above, quality of light is also an important considerationwhen designing an LED dental light, and, specifically, when designingthe illuminators to be used in an LED dental light. For example, it iscommon in the dental setting for dentists to prefer natural light whenperforming certain procedures. Natural light can assist in accuratediagnosis of soft and hard tissue disease and in performingshade-matching. Shade-matching is common during restoration procedures.For example, a patient may seek to have artificial teeth placed in hermouth or to have other dental restoration performed. It is important forthe dentist to be able to match the color of the artificial teeth orrestoration material to the color of the patient's original teeth inorder to produce the most aesthetically pleasing result. Preferably, theshade of the original teeth matches that of the artificial teeth orrestoration material. Natural light is the preferred light fordetermining such a match. However, natural light is not always availablein a dental setting because the matching may be performed at night orinside of a building where windows allowing in natural light are notavailable. Thus, it is desirable for a dental light to mimic naturallight as much as possible if shade-matching applications are to beperformed using the dental light and to facilitate more accuratediagnosis of tissue disease. The closer a dental light is to mimickingnatural light, the higher the quality of light.

Quality of light can be measured in at least three different ways.First, a color rendering index (CRI) can be used. Generally, the higherthe CRI, up to 100, the higher the quality of light. LED dental lightsdescribed herein can have a CRI greater than 85. In some embodiments,the CRI is greater than 88, while in other embodiments the CRI isbetween 87 and 90. However, CRI is not always predictive of quality oflight, or of color rendering performance, of an LED. Thus, otherparameters are often considered when describing the quality of lightemitted from an LED. Quality of light can also be measured bydetermining the correlated color temperature (CCT). CCT is a method fordescribing light color relative to the heating of an ideal blackradiator. Pure white light has a CCT of about 5000 Kelvin (K). Dentalpractitioners commonly prefer the CCT value of a dental light to be asclose as possible to about 5000 K. LED dental lights described hereincan have a CCT of approximately 5000 K. However, the CCT of LED dentallights described herein can be between about 3500 K and about 6500 K.

Quality of light can also be measured by looking to InternationalCommission on Illumination (CIE) chromaticity coordinates. Several CIEstandards exist for determining preferred chromaticity coordinates. ThePlanckian black body locus represents one possible standard, and it isthe standard selected to be used in this application. However, a personof ordinary skill in the art would understand that a different CIEStandard Illuminant, such as D50, D55 or others, could similarly be usedto assess quality of light as discussed herein. In general, light iscloser to mimicking natural light when the CIE chromaticity coordinateslie closer to the Planckian black body locus. In FIG. 10 , the CIE x andy chromaticity coordinates of the Planckian black body locus arerepresented by a line L. LED dental lights described herein arerepresented by lines K. As shown in the figure, the chromaticitycoordinates K of the LED dental lights move towards the Planckian blackbody locus L, demonstrating high quality of light. For example, the opendot represents the CIE chromaticity coordinates (i.e., CIE (x, y)) for aparticular LED light source (e.g., as measured using an integratingsphere or nearly perfect reflective surface). As shown in the figure,the LED light source is more than 0.005 units off of the Planckianlocus, as measured along the length of the line K. The closed dotrepresents the CIE chromaticity coordinates for the particular LED lightsource when incorporated into an LED dental light described herein andas measured at the illumination plane. As shown, the closed dot isapproximately on the Planckian locus, or line L. Thus, the particularLED light source experiences a shift in chromaticity coordinates towardsthe Planckian locus of greater than 0.005 units when it is incorporatedinto the LED dental light. As shown in FIG. 10 , other LED light sourcesrepresented by lines K experience shifts in chromaticity coordinates ofat least 0.002 units, while other sources experience shifts of at least0.004 units.

Although it is preferred that the LED dental light produce high qualityof light, high quality of light may not be required when the LED dentallight is operating in a cure-safe mode. For example, dentists typicallyperform shade-matching and tissue diagnosis when the LED dental light isoperating in a normal mode. If this is the case, cure-safe illuminatorsmay not need to exhibit a CCT close to 5000 K, chromaticity coordinatesclose to the Planckian black body locus, or a high CRI.

The quality of light emitted by an illuminator used in an LED dentallight depends on various different factors. For example, the quality oflight can depend on the quality of light of the particular LED lightsource used in the illuminator. Also, the quality can depend on theoptics selected to be used in the illuminator and how these optics arearranged. Typically, an LED light source with high CRI is preferred.However, optics can be selected so as to improve the CRI of the LEDlight source. Further, an LED light source with chromaticity coordinatesclose to the Planckian black body locus is typically preferred. However,optics can be selected so as to shift the chromaticity coordinates ofthe LED light source towards the Planckian black body locus.

For example, FIG. 8 is a cross-sectional view of an exemplary lenssystem for increasing the quality of light emitted by an LED lightsource. In FIG. 8 , lines 510, 511, 512, 513, 520, 522 represent rays oflight propagating from the LED light source 583. In the illustratedtwo-dimensional view, the area between lines 511 and 513 represents anangular distribution of the light beam emitted from the LED light source583, and the angles of propagation of the light in the light beam can bemeasured from the normal 591, which is perpendicular to the LED lightsource 583 at an approximate center. As shown in the figure, the lightrays 520 and 522 are accepted by the lens 587 and consequently receivedby the lens 588, while the light rays 510 and 512 are rejected by thelens 587. The effective collection angle of the lens 587 is the angledefined by rays 520 and 522. In this manner, the angular distribution ofthe light beam emitted from the LED light source 583 is reduced. Thisreduction in the angular distribution of the light beam emitted from theLED light source improves the quality of light emitted by the LED lightsource 583 by increasing the CRI of the LED and by shifting thechromaticity coordinates of the LED towards the Planckian black bodylocus, as described above with reference to FIG. 10 . As discussedabove, the approach illustrated in FIG. 8 for improving quality of lightis extendable to other CIE standards for determining preferredchromaticity coordinates.

Additionally, the lens system illustrated in FIG. 8 can include anaperture so as to further reduce the angular distribution of the lightbeam emitted from the LED light source 583. In this manner, the aperturewould also function to improve the quality of light emitted by the LEDlight source 583.

The quality of light emitted by the LED light source 583 is improvedbecause the LED light source 583 produces light having a non-uniformdistribution of color. That is, the spectral power distribution (andhence color) of the light within the light beam emitted from the LEDlight source 583 varies as a function of angle as measured from thenormal 591. Typically, the light emitted by an LED light source has anon-uniform spatial and angular distribution of color. For example, thespectral power distribution of the light beam can vary across theangular distribution of the LED and laterally across the emittingsurface of the LED chip. Although the spectral power distribution of thelight within the light beam varies across both a spatial and angulardistribution, this variation in color may be referred to herein simplyas a variation in color across the angular distribution of the lightbeam because the angular variation often dominates.

Because the light beam emitted by the LED light source 583 exhibits suchcolor non-uniformity, reducing the angular distribution of the lightbeam, as shown in FIG. 8 , can increase the CRI of the LED and shift thechromaticity coordinates of the LED in a favorable manner. In someembodiments, the CRI of the LED light source 583 is increased by atleast about two units, while in other embodiments, the CRI is increasedby between two and four units. Reducing the angular distribution of thelight beam emitted from the LED light source 583 functions to improvethe CRI when the portion of the light beam that lies closer to thenormal has a higher CRI than the overall CRI of the LED light source583. By collecting only a central portion of the angular distributionand rejecting the remainder, a higher CRI is achieved. The area of lens587 functions in the illustrated implementation to define an effectivecollection angle and thereby increase the CRI of the LED light source583. In some embodiments, the effective collection angle is less thanabout 60 degrees, while in other embodiments the effective collectionangle is approximately 53 degrees.

The configuration shown in FIG. 8 for improving quality of light iscounter intuitive. Typically, an optical system is designed in order toachieve the highest possible efficiency and illuminance. That is, theoptical system is designed so as to maximize its angle of acceptance, orthe collection angle of the optical elements within the system, in orderto maximize the light received by and transmitted through the opticalsystem. A reduced collection angle, as shown in FIG. 8 , wouldordinarily be viewed by an optics engineer as an inefficiency or adesign flaw. Thus, the configuration shown in FIG. 8 would normally beavoided. Surprisingly, however, reducing the efficiency and illuminanceof an optical system in the described manner can improve the quality oflight emitted by LED dental lights described herein.

Referring back to FIGS. 4, 5, and 7 , a shaping lens can be used toperform a final shaping of the light beams produced by the LED lightsources. In some embodiments described herein, such as the LED dentallight 10 of FIG. 1 , this shaping function is performed by the frontshield 4. FIG. 11A illustrates an example of such a shield. In thefigure, an exemplary LED dental light shield 704 is shown withintegrated shaping lenses 720. The shield 704 is made from a transparentmaterial and can be flat to facilitate cleaning. The shield 704functions to shape light emitted from illuminators positioned behind theshield. In general, the shield 704 refracts the transmitted light alonga refraction axis 710. Correspondingly, this refraction causes the beampattern produced at the illumination plane by the transmitted light tobe elongated within the illumination plane in a direction parallel tothe refraction axis 710.

FIG. 11B is a cross-sectional view taken along the line 11B-11B in FIG.11A. Referring to FIG. 11C, a cross-sectional view taken along the line11C-11C in FIG. 11A provides an enlarged view of the shaping lenses 720.As shown, the shaping lenses 720 are integrated into an inner surface726 of the shield 704. Illuminators as described herein can be incidenton the inner surface 726 so as to transmit light through the shield 704.Also shown is an integrated snap feature 712 which can facilitateattachment of the shield 704 to front housing 714.

FIG. 11D is an enlarged view of the region 11D in FIG. 11C illustratingshaping lens 720 having a width 724 and a height 722. As shown, the lens720 is convex in shape, with respect to illuminators incident on theinner surface 726. Because the lenses 720 extend along the inner surfaceof the shield in a direction perpendicular to the refraction axis 710,the lenses 720 can be referred to as an array of cylindrical lenses.When used with illuminators, the width of the shaping lens 720 istypically such that each illuminator transmits light through more thanone shaping lens 720. That is, the width of the shaping lens 720 istypically less than the width of an illuminator.

Although shaping lenses such as shaping lenses 720 are optional in anLED dental light, such lenses can facilitate accurate positioning orrepositioning of the LED dental light in the direction of therefraction, and therefore improve the experience of a dental patient.Furthermore, because a patient's head may move during the dentalprocedure, it can be desirable for the LED dental light to have an ovalor rectangular-shaped beam pattern at the illumination plane. Theshaping lenses 720 can be configured to refract light so as to assist information of such an oval-shaped pattern.

Another important consideration when designing an LED dental light isproviding a mechanism for dissipation of heat produced by the LED lightsources. Referring to FIGS. 12-14 , in some implementations, LED dentallights described herein are configured to facilitate heat transferbetween the LED light sources and the dental light housing. FIGS. 12-14illustrate views of a specific implementation of the LED dental light ofFIG. 1 . FIG. 13 is a cross-sectional view of the LED dental light 800illustrated in FIG. 12 . In FIG. 13 , a shield 858 is shown connected toa front housing 854, which is attached to a rear housing 850. A gasket857 creates a seal where the shield 858 connects to the front housing854. A central area at 852 of the rear housing 850 can be mounted to apivot assembly to facilitate positioning of the LED dental light 800.

FIG. 14 is an enlarged view of the region 14 in FIG. 13 . As shown, alens module 840 containing a lens 887 is mounted to an optical base 834,which is then mounted to a substrate 830. Also shown is an aperture 884as part of the optical base 834. The rear housing 850 is shown attacheddirectly to the substrate 830 at a pillar or web 871. Optionally, thepillar 871 is integrally formed with the rear housing 850. The area ofattachment between the rear housing 850 and the substrate 830 is at thelocation of the LED light source 883. This type of attachment can bedesirable to facilitate heat transfer between the LED light source 883and the rear housing 850. For example, LED light sources generate heatwhen activated. However, if the heat is not dissipated sufficiently, thelocalized temperature rises and the life expectancy of the LED lightsource can be reduced. The spectral power distribution of the LED lightsource can also be adversely affected by a temperature rise, which cancompromise quality of light produced by the dental light. Thus, amechanism for dissipating heat is preferable. When an LED dental lightis designed in accordance with FIGS. 13-14 , desirable heat dissipationcan be achieved in some embodiments without the need for active coolingor air vents. A lack of air vents can enable the LED dental light 800 tobe a fully enclosed optical system and circuit board, if desired. Such afully enclosed system can reduce contamination and damage to the opticaland electrical components from dust, fluids, or cleaning chemicals.

The pillar 871 can facilitate heat transfer from the LED light source883 to the rear housing 850. In some embodiments, a thermallyconductive, electrically insulating material (such as a pad, gel, paste,etc.) is situated between the rear housing 850 and the substrate 830 atthe area of attachment to further facilitate heat transfer. Althoughheat transfer can be facilitated without the use of a pillar 871, thepillar 871 allows there to be space between the substrate 830 and therear housing 850 to fit electronics that may be attached to thesubstrate 830.

In order to further facilitate heat transfer between the LED lightsource 883 and the rear housing 850, the substrate can be a thermallyconductive printed circuit board, such as any metal clad circuit boardknown in the art. For example, the printed circuit board can have asubstrate (or thermally conductive substrate layer), a dielectric layer,and a circuit layer. The thermally conductive substrate layer cancomprise aluminum, copper or other thermal conductor. Heat transfer maybe improved when the circuit board has a thicker thermally conductivesubstrate layer, a thinner dielectric layer, and copper pours connectedto the LED light sources. In some embodiments, the thermally conductiveprinted circuit board has a total thickness of about 0.056″ or greater,the dielectric layer has a thickness of about 0.003″ (76 microns) orless, the circuit layer has a thickness of about 2 ounces/square feet orgreater, and the copper pours extend from each LED pad with a minimumarea of about 0.07 square inches. The dielectric material can have athermal impedance of about 0.065° C./W and a conductivity of about 1.3W/m-K or greater. However, the dielectric material can have a thicknessof between about 0.0015″ (38 microns) and about 0.009″ (229 microns), athermal impedance of between about 0.3° C./W and about 1.1° C./W, and aconductivity of between about 1.1 W/m-K and about 3.0 W/m-K. Further,the circuit layer can have a thickness of between about 1 ounce/squarefeet and about 3 ounces/square feet.

To further facilitate heat transfer, the rear housing 850 can be made ofa metal or other thermally conductive material. In addition, the LEDlight source 883 can be positioned with respect to other LED lightsources mounted to the substrate 830 so as to reduce localizedtemperature rise. For example, the LED light sources can be positionedwith respect to one another so that the effect from heat produced byneighboring LED light sources is minimized. In one example, the LEDlight sources are spatially separated on the substrate by a distance ofabout 1.4″ or greater. Alternatively, the LED light sources can bespatially separated on the substrate such that there is at least about1″ spacing per 1 Watt of power per LED light source. Further, the LEDlight sources can be coupled to a single substrate or to multiplesubstrates.

LED dental lights as described herein are typically mounted toadditional mechanisms to facilitate positioning by a user. FIGS. 15-18illustrate exemplary mechanisms for positioning an LED dental light.Referring to FIG. 15 , a rear portion of an LED dental light 900 isillustrated attached to an exemplary pivot assembly 948. The LED dentallight 900 has a rear housing 950 and handles 8. The pivot assembly 948can be attached to the rear housing 950 at a central portion 952 that isrecessed into the rear housing 950. The pivot assembly 948 can beattached to the rear housing with exposed screws 944 to allow the LEDdental light 900 to be removed from the pivot assembly 948 to facilitatereplacement and servicing. The pivot assembly 948 can also be attachedto the rear housing 950 with a joint friction adjustment screw 947. Thescrew 947 can use spring tension to clamp a bearing piece into the pivotaxles in order to allow the level of friction in the joint to beadjusted both in the factory and by the end user. The pivot assembly 948includes a pivot arm 946 that is capable of rotational motion into therecess 951 in the rear housing 950. The recess 951 allows the pivotassembly to operate. Also, the recess 951 can allow the pivot assemblyto be attached to the rear housing 950 at the center of mass of the LEDdental light 900. Such a connection can reduce joint friction and makethe joint much easier to operate.

An exploded perspective view of the component parts of the pivotassembly 948 is shown in FIG. 16 . The pivot assembly 948 includes apivot arm 946 with a forked bracket 941. The pivot arm 946 can be hollowso as to allow wires to run through the fork at a wiring passage 945. Inthis manner, movement and bending of the wires can be reduced, whichreduces risk of wiring failure.

The rotational motion of the pivot assembly 948 is illustrated in FIG.17 , which provides a side view of the LED dental light 900 and arm1112. At position 1114, the LED dental light 900 is at a lowerrotational limit, and the pivot arm 946 is fitted within the recess 951.At position 1110, the LED dental light 900 is at an upper rotationallimit. In some embodiments, the total operating range, defined as therange of motion between the upper and lower rotational limit, is atleast 105 degrees.

Referring to FIG. 17 , the LED dental light 900 can be attached by thepivot assembly 948 to the arm 1112. For example, as shown in FIG. 16 , apivot housing 943 can be connected to the pivot arm 946 by a plasticsleeve bearing 942, a rotation stop 937, and a joint friction adjustmentscrew 938. The pivot housing 943 can then be connected to an arm 1112.The rotational motion of this attachment is shown in FIG. 18 , whichprovides a front view of the LED dental light 900 and the arm 1112. Atposition 1116, the LED dental light 900 is in a first rotationalposition. At position 1117, the LED dental light 900 is in a secondrotational position. A total operating range, defined as the range ofmotion between the first and the second rotational positions, can be atleast 80 degrees in some embodiments.

In some embodiments, the arm 1112 can have indicators 1115, asillustrated in FIGS. 17 and 18 . The indicators can be backlitilluminated regions or other illuminated displays, and, although aseries of indicators 1115 are shown in the figures, more or fewerindicators can be provided. The indicators 1115 can indicate the currentoperating setting of the LED dental light, or other light functionality.Exemplary operating settings include, but are not limited to, intensitysettings, normal-mode operation, or cure-safe operation. For example,the indicators can indicate to an operator viewing the indicators whatintensity (e.g., illuminance) setting, or other functional setting, iscurrently selected. Additionally, the indicators can indicate how manytimes a selector switch must be actuated to select the cure-safe mode.In one implementation with a series of four indicators, illumination ofone of the indicators can indicate care-safe operation, whileillumination of the other three indicators (individually or incombination) can indicate which of three illuminance settings areactivated during normal mode operation. In one implementation with asingle indicator, the single indicator can change in appearance based onthe current operating setting. For example, the indicator can change incolor, display different numbers, or display different pictures orgraphics based on the current operating setting.

Although the indicators 1115 are shown in a particular location on arm1112, the indicators can be placed in a different location. However, itis preferable that the indicators be positioned so that viewing by anoperator is convenient and not difficult. For example, it is preferablethat an operator be able to quickly recognize the setting of the dentallight from various different viewing angles. Indicators 1115 located onor near to the dental light 900 are generally convenient for viewing byan operator. But, indicators 1115 located directly on or adjacent to thefront face of the LED dental light 900 may be obstructed from theoperator's view in some circumstances. For example, because the dentallight 900 is mounted to a pivot arm 946 and capable of pivoting aboutone or more axes, the orientation of indicators located on the dentallight can vary, thereby making it more difficult for an operator toquickly locate and interpret the information provided by the indicators.Furthermore, an operator may have difficulty seeing the front face ofthe dental light 900 during some dental procedures, particularly if theoperator is seated to the side or at an elevated position relative tothe dental light 900. Thus, it may not be desirable to locate theindicators 1115 directly on or adjacent to the front face of the LEDdental light 900.

For more convenient viewing, it is generally desirable to position theindicators 1115 such that the orientation of the indicators is minimallyobstructed by the position of the dental light 900 and such that theindicators 1115 are viewable from a wide range of viewing anglesrelative to the front view of the arm 1112 (as shown in FIG. 18 ). Forexample, referring to FIGS. 17 and 18 , the indicators 1115 maintainvertical orientation (i.e., the indicators may move up and down, butwill not rotate side to side or tilt forward or back) despiterepositioning of the dental light 900 because the arm 1112, as shown,pivots about one axis only—the vertical axis. Further, regardless of therotational motion of the LED dental light 900, the indicators 1115remain substantially unobstructed from the front and side views shown inFIGS. 17 and 18 . In addition, the forward facing surface of the arm1112 (shown in FIG. 18 ) can be curved, and the indicators 1115 toextend laterally along this curved surface. In this manner, theindicators 1115 can be viewable from a wide range of viewing angles. Forexample, as shown in FIG. 17 , such a curved surface facilitates viewingof the indicators 1115 from the side, which is a viewing angle of 90degrees relative to the front view of the arm 1112. Such a curvedsurface can also facilitate viewing from viewing angles of more than 90degrees relative to the front view of the arm 1112.

LED dental lights as described herein are typically implemented withvarious electronics for controlling functions of the light. Suchelectronics can be included within the housing of the LED dental light,or as part of the separate housing. In an exemplary implementation of adual-mode LED dental light, the LED light sources of the dental lightcan be controlled by an LED driver capable of supporting dual-modeoperation. The LED driver can be a single or multichannel LED currentregulator configured to provide multichannel output and buck-boostcurrent regulation (i.e., a so-called buck-boost regulator). Thebuck-boost regulator can be selected from those known in the art. Insome embodiments, the buck-boost regulator is a Single-Ended PrimaryInductance Converter (SEPIC). A buck-boost regulator can provide anoutput voltage necessary for a specific load regardless of therelationship between the input voltage and the output voltage. Thisallows the driver to drive two different loads, and thereby support bothnormal and cure-safe modes of operation. For example, a buck-boostcurrent regulator allows an input voltage to be greater, equal, or lessthan the output voltage.

Such a current regulator can maintain color consistency of the LED lightsources by maintaining consistent current to each LED. The LED lightsources can be arranged in series and connected to the currentregulator. When connected in series, LED protection devices can beincluded to allow for current to flow through each LED regardless of anLED failure. Pulse-width modulation (PWM) dimming can allow forconsistent color and CRI when dimming. Analog dimming can be used toreduce the intensity, however, analog dimming is nonlinear and can skewCCT and CRI. As consistent color and CRI are desired for all modes ofoperation, PWM dimming is usually preferred.

The LED driver can dynamically regulate current through two strings ofLED light sources. For example, the first string can connect LED lightsources dedicated to normal-mode operation. This mode can also be calleda white light mode. The second string can connect LED light sourcesdedicated to a cure-safe operation. A user of the LED dental light cancontrol whether the LED dental light operates in cure-safe or normalmode. Typically, the LED light sources will be connected in series.Because the LED lights are dedicated to a particular mode, the LED lightsources in the first string will not typically be activated at the sametime as the LED light sources in the second string, and vice versa. Thestrings can operate independently of each other. That is, the stringscan be arranged in parallel with respect to each other. The first stringcan be connected to a first output of the LED driver and the secondstring can be connected to a second output of the LED driver.

As discussed above, the LED driver can be capable of dimming. Forexample, the LED driver can be configured to provide a plurality of PWMlevels of dimming when a string is activated. For example, when the LEDdental light is in normal-mode operation, the LED driver can producethree levels of intensity output. The level of intensity output can beselected by the user. In one implementation, a high illuminance settingproduces light having an intensity of between about 25,000 lux and35,000 lux, a medium illuminance setting produces light having anintensity of between about 18,000 lux and 30,000 lux, and a lowilluminance setting produces light having an intensity of between about10,000 lux and 20,000 lux. Further, cure-safe operation produces lighthaving an intensity of between about 18,000 lux and 30,000 lux. Inanother implementation, a high illuminance setting produces light havingan intensity of about 30,000 lux, a medium illuminance setting produceslight having an intensity of about 25,000 lux, and a low illuminancesetting produces light having an intensity of about 15,000 lux. Further,cure-safe operation produces light having an intensity of about 25,000lux.

Referring to FIG. 21 , an exemplary LED driver 1210 is shown within anexemplary LED control circuit 1200. The LED driver 1210 can include abuck-boost current regulator 1220. The LED light sources 1230 areorganized into two strings: normal-mode LED light sources 1270 andcure-safe LED light sources 1280. The LED driver 1210 has a first output1212 that electrically couples the driver to the string of normal-modeLED light sources 1270. The LED driver 1210 also has a second output1214 that electrically couples the driver to the string of cure-safe LEDby sources 1280. Thus, the LED driver 1210 is configured to operate adual-mode LED dental light.

In general, operation of the LED dental light can be controlled by auser. FIG. 22 illustrates an exemplary control system 2200 for an LEDdental light. As shown, a user provides input 2212 to the dental lightcontrol system via a communications interface 2210. For example, theuser may provide input to the control system via a mechanical switch,series of buttons, interactive display, mouse, keyboard, or other deviceknown in the art for facilitating user control of a system. The userinput 2212 may correspond to a request that the dental light be placedin cure-safe or in normal-mode operation, a request to turn the dentallight on or off, a request to change intensity of the light, or totrigger other functionality of the dental light. The user input is thentransmitted as a command or message via a controller-area network(CANbus) cable 2214.

The CANbus cable 2214 provides a means for communicating data, such asmessages and commands, between control circuits 2230, the LED driver2220, and the communication interface 2210. The CANbus cable 2214 canalso function to transmit power to the LED light sources. For example,the CANbus cable 2214 can operate as a combo-cable, combining datacommunication and power.

The control circuits 2230 represent electronics connected to the LEDdental light configured to perform other functionalities of the LEDdental light. The LED driver 2220 is shown connected to the LED lightsources 2240. The LED driver 2220 can receive data via the CANbus cable2214 and control the LED sources 2240 in the appropriate manner. Forexample, if the LED driver 2220 receives a message via the CANbus cable2214 to turn the LED dental light on, the LED driver 2220 can respond byactivating LED light sources 2240.

In view of the many possible embodiments to which the principles of thedisclosed invention may be applied, it should be recognized that theillustrated embodiments are only preferred examples and should not betaken as limiting in scope. Rather, the scope is defined by thefollowing claims. We therefore claim all that comes within the scope andspirit of these claims.

We claim:
 1. A dental light, comprising: at least one light emittingdiode (LED) light source mounted to a substrate and configured toproduce a light beam along a normal axis that is perpendicular to thesubstrate at an approximate center of the at least one LED light source,the light beam containing light having a plurality of angles ofpropagation relative to the normal axis and the plurality of anglesrepresenting an angular distribution of the light beam; and at least onecollimating lens system situated to receive the light beam andcomprising an aperture situated directly downstream from the lightsource and configured to shape the light beam as emitted from the lightsource such that the angular distribution as emitted from the lightsource is reduced along a first axis perpendicular to the normal axis,thereby producing a shaped light beam, wherein the reduced angulardistribution along the first axis corresponds with a reduction inpatient eye glare at a predetermined illumination plane.
 2. The dentallight of claim 1, wherein the at least one collimating lens systemfurther comprises a total internal reflection (TIR) collimator, the TIRcollimator configured to mix light within the light beam to furtherincrease color uniformity of the light beam.
 3. The dental light ofclaim 2, wherein the collimating lens system further comprises adiffuser configured to mix light within the light beam by controlleddiffusion to further increase color uniformity of the light beam.
 4. Thedental light of claim 3, wherein the diffuser is positioned downstreamfrom the TIR collimator and the aperture is positioned upstream from theTIR collimator; wherein the at least one collimating lens system furthercomprises a condenser lens situated downstream from the diffuser, thedental light further comprising at least one shaping lens situateddownstream from the condenser lens.
 5. The dental light of claim 1,wherein the at least one collimating lens system further comprises alens and a total internal reflection (TIR) collimator situated upstreamof the lens, the TIR collimator configured to mix light within the lightbeam to increase color uniformity of the light beam.
 6. The dental lightof claim 5, wherein the lens comprises a collector lens, a condenserlens, or both a collector lens and a condenser lens.
 7. The dental lightof claim 6, wherein the at least one collimating lens system comprisesat least one shaping lens configured to modify the shape of the lightbeam at the predetermined illumination plane.
 8. The dental light ofclaim 1, wherein the aperture has a substantially rectangular shape andthe at least one collimating lens system comprises collimating optics,wherein the aperture is positioned between the LED light source and thecollimating optics, the aperture having a short axis that corresponds tothe first axis extending perpendicular to the normal axis, and furthercomprising at least one shaping lens situated downstream from thecollimating optics, the at least one shaping lens being configured toreceive the shaped light beam and to spread the light beam in theillumination plane to further reduce patient eye glare.
 9. The dentallight of claim 1, wherein the at least one collimating lens system issituated to receive the light beam and configured to mix light withinthe light beam by controlled diffusion to increase color uniformity ofthe light beam.
 10. The dental light of claim 1, wherein the reducedangular distribution of the light beam is configured to improve aquality of light emitted by the LED light source by increasing a colorrendering index (CRI) of the LED light source and by shifting thechromaticity coordinates of the light beam towards the Planckian blackbody locus.
 11. A dental light, comprising: at least one light emittingdiode (LED) light source mounted to a substrate and configured toproduce a light beam along a normal axis that is perpendicular to thesubstrate at an approximate center of the at least one LED light source,the light beam containing light having a plurality of angles ofpropagation relative to the normal axis and the plurality of anglesrepresenting an angular distribution of the light beam; and at least onecollimating lens system situated to receive the light beam andcomprising an aperture configured to shape the light beam such that theangular distribution as emitted from the light source is reduced along afirst axis perpendicular to the normal axis, thereby producing a shapedlight beam, wherein the reduced angular distribution along the firstaxis corresponds with a reduction in patient eye glare at apredetermined illumination plane; wherein the at least one collimatinglens system further comprises a lens and a total internal reflection(TIR) collimator situated upstream of the lens, the TIR collimatorconfigured to mix light within the light beam to increase coloruniformity of the light beam.
 12. The dental light of claim 11, whereinthe lens comprises a collector lens, a condenser lens, or both acollector lens and a condenser lens.
 13. The dental light of claim 12,wherein the at least one collimating lens system comprises at least oneshaping lens configured to modify the shape of the light beam at thepredetermined illumination plane.